Influence of dough sheeting, flour pre-gelatinization and zein inclusion on maize bread dough functionality

Abstract

Developing tropical countries need simple technologies to enable the production of bread from locally produced cereals, such as maize and sorghum. However, current gluten-free bread making technology relies heavily on the addition of additives, which results in products that are nutritionally inferior to wheat breads. Hence, this study investigated the technologies of flour pre-gelatinization and dough sheeting plus addition of commercial zein to improve maize dough functionality and bread quality. A strong and cohesive maize flour dough could be produced as a result of uniform incorporation of a 30% of pre-gelatinized maize flour through repeated dough sheeting. Pre-gelatinized starch acts as a hydrocolloid and the dough viscosity was probably increased through the hydroxyl groups of the hydrocolloidal structure enabling more interactions with water molecules. The dough still lacked extensibility. However, extensibility and gas-holding were significantly improved by additionally incorporating an α-zein viscoelastic mass above its glass transition temperature into the dough during sheeting. The zein fibrils appeared to entrap the maize flour particles. Zein inclusion also improved bread crumb cell structure and increased loaf volume somewhat. However, the crumb cell walls were much thicker than in wheat bread and comprised clumps of starch granules.